The most intriguing difference is how easily you find complex organics on Saturn’s moon Enceladus compared to Mars. If you consider the enormous efforts put into the search for organics on Mars since the 1970s without success, it’s just amazing how easily we found complex and diverse organic chemistry on Enceladus with a spacecraft flying by. However, it’s a huge success that NASA’s Curiosity finally found organics on Mars. From what I read, the organics on Mars – like the Enceladean ones – could be large molecules that contain aromatic and aliphatic structures. Whereas we find oxygen and probably nitrogen in both organic molecules, the Mars organics do contain sulphur. The Cassini instruments were not very sensitive to sulphur, so it might be the case that it’s there as well without us noticing it.
On Mars, over 50 space missions with several generations of
